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Metamath Proof Explorer
Description: Theorem *4.45 of WhiteheadRussell p. 119. (Contributed by NM, 3-Jan-2005)
|
|
Ref |
Expression |
|
Assertion |
pm4.45 |
⊢ ( 𝜑 ↔ ( 𝜑 ∧ ( 𝜑 ∨ 𝜓 ) ) ) |
Proof
| Step |
Hyp |
Ref |
Expression |
| 1 |
|
orc |
⊢ ( 𝜑 → ( 𝜑 ∨ 𝜓 ) ) |
| 2 |
1
|
pm4.71i |
⊢ ( 𝜑 ↔ ( 𝜑 ∧ ( 𝜑 ∨ 𝜓 ) ) ) |